Struct CancelToken 

pub struct CancelToken { /* private fields */ }

A handle into a cancel subtree.

Clone yields the same identity (same node), like the legacy token. A cancel() cancels this token’s own subtree (epoch/fetch cancels are legitimate); ancestors and siblings are unaffected. Two constructors mint a fresh subtree root instead of deriving from a parent — root, the owning master a subsystem holds and cancels on teardown, and never, a sentinel that is never cancelled. Both are covered by the cancel_root_sites guard.

Implementations

impl CancelToken

pub fn cancel(&self)

Cancel this token’s subtree.

pub fn cancelled(&self) -> Cancelled<'_>

Future that resolves once this token’s subtree is cancelled. Cancel-safe in tokio::select!: dropping it unregisters its slot.

pub fn child(&self) -> Self

Derive a child token rooted at this token’s subtree.

pub fn is_cancelled(&self) -> bool

pub fn never() -> Self

A token that is never cancelled — a placeholder where a token is required but no cancellation source exists. The sentinel sibling of root; both mint a fresh subtree root.

pub fn on_cancel<F>(&self, waker: F) -> CancelWakerGuard

where F: Fn() + Send + Sync + 'static,

Register a synchronous waker fired when this token is cancelled — the sync counterpart to cancelled for a thread parked on a (flash-aware) Condvar/Notify. Registered on THIS node only; an ancestor cancel() reaches it through the down-propagation drain.

The waker runs on the cancelling thread: keep it cheap, non-blocking, and idempotent. If the token is already cancelled it fires immediately. The returned guard unregisters the waker on drop — hold it for the wait’s lifetime.

pub fn root() -> Self

Mint a fresh root of a new cancel subtree — the owning master a subsystem holds and cancels on teardown. Drop is passive: dropping the root does not cancel its subtree; teardown is an explicit cancel(). Minted only at owner sites (enforced by the cancel_root_sites guard). For a token that is structurally required but never cancelled, use never instead.

Trait Implementations

impl BitOr<CancelGroup> for CancelToken

type Output = CancelGroup

The resulting type after applying the | operator.

fn bitor(self, rhs: CancelGroup) -> CancelGroup

Performs the | operation.

impl BitOr<CancelToken> for CancelGroup

type Output = CancelGroup

The resulting type after applying the | operator.

fn bitor(self, rhs: CancelToken) -> Self

Performs the | operation.

impl Clone for CancelToken

fn clone(&self) -> CancelToken

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CancelToken

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<CancelToken> for CancelGroup

fn from(token: CancelToken) -> Self

Converts to this type from the input type.